A thread on a forum I belong to asks what moments of otherkin related happiness one has recently had. It occurred to me that my most recent moment of true happiness (and great achievement) had nothing to do with otherkin at all. I finished a half marathon yesterday...and surprisingly I had zero shifts along the way. It's especially suprising since I almost always have some form of shift when I run. Usually claws and teeth seemingly belonging to some flavor of large feline or the urge to track something down or just let loose and let fly.
What really got me in thinking about it was that the entire race was a fully human experience, probably my first ever. I have no explanation for it, just theories. Maybe the sheer exhaustion of it all? But then, that didn't kick in until mile 7...so that's 7 miles I usually shift during. I don't know, but whatever the reason it was actually wonderful to have such a human experience. I can't say what it means or if it'll ever happen again, but there you have it.
It also could have been if you were concentrating on something. The dopamine rush could attribute as well, but be careful of that, as you can actually expend too much and risk some major complications.
I would like to point out that you said "It's especially suprising since I almost always have some form of shift when I run."-So it might not even be an entirely new experience, just the first one that has lasted a long time or the first one you thoroughly noticed.